EP2640567B1 - Method and device for producing large cylindrical structures - Google Patents

Description

The invention relates to a method for producing large cylindrical structures or large moldings, in particular fuselage parts for aircraft, made of fiber-reinforced plastic, wherein in a mold space between a cylindrical inner mold and a cylindrical outer shape fibers, preferably one or more semi-finished fiber products, and a curable plastic material are introduced wherein the cylindrical inner shape is composed of a plurality of circumferentially distributed inner segments and the outer shape is composed of a plurality of circumferentially distributed outer segments. The plastic compound is then cured. The plastic composition is typically a thermoset plastic compound used in the manufacture of fiber reinforced plastics, and hence fiber composites. The fibers are embedded in a plastic matrix. The fibers may be z. As to glass fibers and / or carbon fibers or carbon fibers, but also to other types of fibers. The fibers may be present loosely, but preferably in the form of semi-finished products, as fiber mats or the like. Large structure or large shaped part means in particular a cylindrical molded part with a diameter of at least 2 m, preferably at least 3 m. It may be particularly preferred to hull parts for aircraft.

It is known in the construction of aircraft fuselages, esp. Tubular, esp. Ton barrel fuselage sections individually prefabricate and assemble in a subsequent final assembly to the finished fuselage. As materials are increasingly fiber composites such. As carbon fiber reinforced plastics (CFRP) used. In this way, aircraft fuselages with high stability and low weight can be produced.

From the DE 10 2007 060 029 A1 there is known a method of manufacturing a tubular structural member, wherein a tubular molding tool is provided having an inner molding surface formed corresponding to an outer surface of the structural member. The inner mold surface is formed by an expandable carrier which is shaped to fill the mold in an unexpanded state leaving an expansion distance of the carrier surface to the mold surface. The carrier is placed in the mold and the fiber layer is pressed against the mold surface by expanding the carrier. Subsequently, the fiber fabric is infiltrated with a curable matrix.

A generic method for producing fuselage parts for aircraft construction of the type described above is for example from the US 2010/0155984 A1 known.

In order to automate the production of fuselage parts for aircraft construction, for example, the use of automated winding machines for semi-finished fiber products has also been proposed (cf. US Pat. No. 7,048,024 B2 ).

From the field of container technology, it is pressure vessels, z. B. for nuclear installations, incidentally, set up on the pressure vessel outside biasing units, which are wound with a winding device biasing elements in the form of ropes (see. DE 27 16 020 ). On the construction of, for example, fuselage parts for aircraft construction such developments had no influence.

The invention has for its object to provide a method with which large structures or large moldings, esp. Fuselage parts for aircraft Made of fiber-reinforced plastic, economically manufactured with high quality.

To solve this problem, the invention teaches in a generic method for producing cylindrical large structures or large moldings that the outer segments with one or more tension cables which are wound around the outer mold or the outer segments, with the interposition of fibers or semi-finished fiber products against the inner mold be tense.

The invention is initially based on the recognition that the finished large structures or large moldings can be easily removed after molding when the inner mold consists of several inner segments, so that they can be removed in a simple manner "inside". This has the advantage, in particular in the case of materials with a negative temperature coefficient, which consequently contract in the course of hardening, that simple demolding of the component succeeds. But also the outer shape consists of several distributed over the circumference outer segments, so that in addition an improved handling is realized. Nevertheless, in such an embodiment, the high forces occurring in the course of shaping or curing can be absorbed in a simple manner, because the outer shape is braced against the inner shape with the aid of tensioning cables wound around the outer shape. This achieves a simple design of the mold, a simple production and in particular a simple removal of the mold or a simple demolding of the finished component.

Preferably, the inner mold is first assembled from the inner segments and then the fibers or semifinished fiber products are subsequently applied to the inner mold applied, z. B. wound around the inner mold. Thereafter, the outer shape of the individual outer segments is placed or assembled and clamped by means of the tension cables. Finally, the molding material is then introduced into the mold space, for. B. injected. It is expedient to temper the mold before and / or during molding, preferably to heat. The molding compound then cures to include the fibers.

Taking into account the fact that, for example, fuselage parts for aircraft are usually provided with stiffening elements, the invention proposes in a preferred embodiment that before placing the outer shape and preferably before the application of the fibers or semi-finished fiber stiffening elements, eg. As stringers, frames o. The like. Be placed on the inner mold. For this purpose, the inner mold on its outer surface facing the outer surface and consequently on the molding surface as a rule on recesses as quasi recordings for the stiffening elements. The stiffening elements may be, for example, bent frames and / or longitudinal stringers. In the manner described, such stiffening elements, which are common in aircraft construction, can be easily integrated into the manufacturing process according to the invention.

In order to remove the finished molded part from the mold, the invention further proposes first to remove the inner mold by preferably the individual inner segments are pulled together in the radial direction. For this purpose, it is expedient to separate the inner segments at their abutting end faces from each other and then fold inward as it were. The inner segments (or several inner segments) may possibly be pivotally connected to each other but also be formed of individual parts. In this case, the abutting end faces or abutting surfaces of the individual segments are preferably designed so that in the assembled state, a stable structure is formed, which withstands the pressure of the tensioned outer shape. For this purpose, it may be useful in the course of assembling the inner mold between the last used inner segments a stabilizing component, for. B. a stabilizing wedge, a stabilizer bar o. The like. Use. In the course of demoulding, this is first removed, so that then the inner segments can be easily folded inwards.

In a modified embodiment, there is the possibility that the individual inner segments are fastened together to an automated contraction device with which the individual inner segments are pulled inward or inward in the radial direction via one or more suitable drives. Such a contraction device can, for. B. have a central holder or a central hub, on which the individual inner segments are pivotally connected with the interposition of connecting rods. By turning the central holder, the individual inner segments can then be pulled inwards via the connecting rods. About the connecting rods, which are then aligned during the manufacturing process in the radial direction, and relatively high forces can be absorbed.

In the context of the invention it depends, inter alia, on the composite outer shape of the described tension cables, z. B. steel cables, wind up. For this purpose, a winding device is usually provided. Particularly preferably, the composite form is rotated to wind up the tensioning cables themselves and thereby the ropes are unwound from a cable reel or from several cable reels. In this way it is avoided to transport the heavy rope reels over long distances around the stationary form. Rather, the reels can be arranged stationary. Instead, the mold is rotated by means of a suitable drive, so that the ropes are pulled off and wound up.

The invention also relates to an apparatus for producing cylindrical large structures or large moldings, esp. Hull parts for aircraft construction with a method of the type described. In the context of the invention, this device has an inner shape which is composed of a plurality of inner segments and an outer shape, which is composed of several outer segments. Further, a winding device for wrapping the outer mold is provided with the tension cables. The winding device preferably has one or more cable reels, from which the ropes are unwound. In this case, the winding device preferably has a rotary receptacle for the mold, wherein the mold is mounted on or on this rotary receptacle and wherein the rotary receptacle is formed with a rotary drive for rotating the mold in the course of unwinding the steel cables.

In order to facilitate the winding of the ropes on the outer shape or the outer segments and to ensure a uniform tension, the invention proposes in a preferred embodiment that the outer shape or its outer segments on the outside have at least one spirally encircling groove or groove, in which the Tensioning cables inserted during the wrapping or in which the tensioning cables are guided.

The inner mold and / or the outer mold or their segments are preferably equipped with heating channels and / or cooling channels for tempering the mold before and / or during curing. In addition, the mold is equipped with suitable feed channels through which the curable molding material can be introduced into the mold space, for. B. is injectable. Particularly preferably, the supply of the molding compound takes place via the inner mold. For this purpose, a plurality of feed channels aligned in the radial direction can be introduced into the inner mold, which open into the mold space. These feed channels are connected to corresponding mixing heads or spray heads, which can be attached to the inside of the inner mold.

Overall, in the context of the invention, large structures or large moldings made of fiber-reinforced plastic, esp. Hull parts for aircraft, can be produced in a simple manner economically with high quality.

Fig. 1

ausschnittsweise eine Innenform für die Herstellung eines Rumpfteils für den Flugzeugbau mit einem eingelegten Verteilerpaket,

Fig. 2

den Gegenstand nach Fig. 1 mit eingelegten Versteifungselementen und aufgebrachtem Faserhalbzeug,

Fig. 3

die vollständige Innenform mit Versteifungselementen während des Aufwickelns des Faserhalbzeuges,

Fig. 4

den Gegenstand nach Fig. 2 mit aufgebrachter Außenform und zum Teil aufgewickelten Stahlseilen,

Fig. 5

die gesamte Form mit zum Teil aufgewickelten Stahlseilen (entsprechend Fig. 4),

Fig. 6

den Gegenstand nach Fig. 5 in einer Stirnansicht zu Beginn des Entfernens der Innenform,

Fig. 7

den Gegenstand nach Fig. 6 während des Entfernens der Innenform,

Fig. 8

den Gegenstand nach Fig. 7 in einer perspektivischen Darstellung während des Entfernens der Außenform,

Fig. 9

eine Wickelvorrichtung in einer ersten Ansicht,

Fig. 10

eine Wickelvorrichtung in einer zweiten Ansicht, und

Fig. 11a, b, c

eine abgewandelte Ausführungsform der Erfindung (Ausschnitt).

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. Show it

Fig. 1

a detail of an inner mold for the production of a fuselage for aircraft construction with an inserted distribution package,

Fig. 2

the object after Fig. 1 with inserted stiffening elements and applied semi-finished fiber products,

Fig. 3

the complete inner shape with stiffening elements during the winding of the semifinished fiber product,

Fig. 4

the object after Fig. 2 with applied outer shape and partly wound steel cables,

Fig. 5

the entire form with partly wound up steel cables (according to Fig. 4 )

Fig. 6

the object after Fig. 5 in an end view at the beginning of the removal of the inner mold,

Fig. 7

the object after Fig. 6 while removing the inner mold,

Fig. 8

the object after Fig. 7 in a perspective view during the removal of the outer shape,

Fig. 9

a winding device in a first view,

Fig. 10

a winding device in a second view, and

Fig. 11a, b, c

a modified embodiment of the invention (detail).

With the method shown in the figures and with the device shown in the figures can be cylindrical large structures, eg. B. fuselage parts for aircraft manufacture of fiber-reinforced plastic.

The mold for the production of such large structures consists of on the one hand an inner mold 1 and on the other hand an outer mold 2, wherein between the inner mold and outer mold, a mold space 3 is formed. Within the mold space 3 are semi-finished fiber products 4 are arranged and for producing the molded part is then introduced into the mold space 3, the curable plastic material 5 as a matrix.

The inner mold 1 according to the invention consists of a plurality of inner segments 1a distributed over the circumference and the outer mold 2 consists of a plurality of outer segments 2a distributed over the circumference.

The assembly of the mold and the production of the molding can be determined by a comparative consideration of Fig. 1 to 5 explain.

Fig. 1 initially only partially shows the inner mold 1 or in a perspective section an inner segment 1a. It can be seen that this inner segment is provided with recesses 6, in which stiffening elements 7a, 7b are used. The stiffening elements are, on the one hand, stringer 7a extending in the longitudinal direction of the cylinder and, on the other hand, bent and thus circumferentially extending frames 7b.

After the stiffening elements 7a, 7b were inserted into the recesses or receptacles 6, the semifinished fiber 4 is applied, preferably wound. This results from a comparative analysis of the Fig. 2 and 3 ,

After the semi-finished fiber 4 has been completely wound up, the outer mold 2 is placed, which consists of the outer segments 2a. To the outer mold 2 tensioning cables 8 are then wound, ie the outer mold 2 is clamped with the interposition of the semifinished fiber 4 against the inner mold 1 by means of the tension cables 8. The Fig. 4 and 5 show thereby in different Views the shape consisting of inner mold 1 and outer mold 2 with partially wound tension cables. 8

After the outer mold 2 has been completely clamped against the inner mold 1, the plastic molding compound 5 can be injected into the mold space 3. This is indicated by the arrows 5.

It can be seen that for introducing the molding compound, the inner mold 1 is provided with (radially oriented) channels 9, which in turn are connected to spray heads or mixing heads 10. The spray heads or mixing heads 10 are attached to the inside of the inner mold 1.

Before and / or during the curing of the molding compound, the inner mold 1 and / or the outer mold 2 are tempered. For this purpose, both the inner mold 1 and the outer mold 2 are provided with heating channels 11, which run in the embodiment in the longitudinal direction of the cylinder. They are only indicated for the inner shape. By tempering the molding compound 5 hardens including the fibers or the semifinished fiber 4, so that the produced large-shaped part, z. B. a body part is created.

To be able to remove this finished molded part F from the mold, the inner mold 1 is preferably first removed. This results from a comparative analysis of the Fig. 6 to 8 ,

In Fig. 6 It can be seen that initially between two joints of two adjacent inner segments 1a a locking wedge or locking bar 12 is removed, which can also be referred to as a head piece or capstone, so that the inner shape as it were folded radially inward and can be taken ( Fig. 7 ). Subsequently, the outer mold 2, which consists in the embodiment of two segments 2a, unfolded (see. Fig. 8 ), so that the finished molded part F can be removed.

The winding of the tensioning cables 8 is of particular importance in the context of the invention. For this purpose, the invention in a preferred development, a winding device 13 for winding the steel cables on the outer mold 2 available. In the illustrated exemplary example, this winding device has two cable reels 14, of which the steel cables 8 are unwound. Furthermore, the winding device 13 has a rotary device 15 for the mold, which is composed of inner mold 1 and outer mold 2. This rotary device 15 or rotary holder is provided with a rotary drive 16. Consequently, for winding the steel cables 8 on the outer mold 2, the mold 1, 2 rotated by means of the rotating device 15, so that the steel cables 8 are deducted from the cable reels 14 (see. FIGS. 9 and 10 ).

To ensure proper winding of the steel cables on the outer mold 2, the outer mold 2 is provided with grooves or grooves 17. In the exemplary embodiment is a groove 17 arranged spirally on the outer circumference of the outer mold 2. The cable reels 14 are displaceable in the longitudinal direction L of the mold in order to be able to wind the tensioning cables successively.

Furthermore, the multi-part inner mold 1 in the context of the invention is of particular importance, since the contraction of the inner mold 1, a simple demolding of the component is possible. A first embodiment was based on the Fig. 6 to 8 been explained. A modified embodiment show the Fig. 11a, 11b and 11c ,

In this embodiment, the inner segments 1a are connected to an automated contraction device 18. This contraction device has a central holder or central hub 19, with which the inner segments 1a are pivotally connected with the interposition of connecting rods 20. A comparative analysis of the Fig. 11a, 11b and 11c shows that by rotating the central hub 19, the inner segments 1a can be automatically retracted.

With the described method and the device described, large structures with a diameter of more than 3 m, particularly preferably more than 4 m, are preferably produced. In such a case, the inner mold and / or the outer mold preferably have a wall thickness of more than 50 mm, preferably more than 80 mm, z. B. 100 mm or more. The tensioning cable is preferably a steel cable which has a diameter of more than 10 mm, preferably more than 20 mm, z. B. may have 30 mm or more.

Claims (11)

1. A method for the manufacture of large cylindrical structures and/or large moulded parts (F), in particular fuselage parts for aircraft construction from fibre-reinforced plastic, wherein fibres, preferably one or a plurality of semi-finished fibre products (4), and a curable plastic material (5) are introduced into a moulding cavity (3) between a cylindrical inner mould (1) and a cylindrical outer mould (2), wherein
   the cylindrical inner mould (1) is composed from a plurality of inner segments (1a) distributed over the periphery, and the outer mould (2) is composed from a plurality of outer segments (2a) distributed over the periphery,
   characterised in that,
   the outer segments (2a) are clamped against the inner mould (1), with the interposition of the fibres, and/or semi-finished fibre products (4), with one or a plurality of tension cables (8), which are wound around the outer segments (2).
2. The method in accordance with Claim 1, characterised in that,
   the inner mould (1) is firstly composed from the inner segments (1a),
   the fibres, or at least one semi-finished fibre product (4), are then applied onto the inner mould (1), e.g. are wound onto the inner mould,
   the outer mould (2) is then set in place and clamped by means of the tension cables (8), and
   finally the moulding material (5) is introduced into the moulding cavity (3), e.g. is injected into the latter.
3. The method in accordance with Claim 1 or 2, characterised in that, before the outer mould (2) is set in place, and preferably before the application of the fibres and/or semi-finished fibre products (4) stiffening elements (7a, 7b), e.g. stringers, frames, or similar, are set in place on the inner mould (1), e.g. in recesses (6) on the outer face of the inner mould (1).
4. The method in accordance with one of the Claims 1 to 3, characterised in that, for purposes of removing the finished moulded part (5) from the mould the inner mould (1) is contracted, e.g. by separating the individual inner segments (1a) from one another, and/or pivoting them relative to one another.
5. The method in accordance with one of the Claims 1 to 4, characterised in that, the composed mould (1, 2) is rotated for purposes of winding on and tensioning the tension cables (8), and at the same time the tension cables (8) are unwound from at least one cable reel (14).
6. A device for the manufacture of large cylindrical structures and/or large moulded parts, in particular fuselage parts for aircraft construction from fibre-reinforced plastic, in accordance with a method in accordance with one of the Claims 1 to 5,
   with an inner mould (1), which is composed from a plurality of inner segments (1a), and an outer mould (2), which is composed from a plurality of outer segments (2a), and
   with a winding device (13) for purposes of winding the tension cables (8) around the outer mould (2),
7. The device in accordance with Claim 6, characterised in that, the winding device (13) has one or a plurality of cable reels (14), from which the tension cable (8) can be unwound.
8. The device in accordance with Claim 6 or 7, characterised in that, the winding device (13) has a rotary holding fixture (15) for the mould (1, 2), wherein a rotary drive (16) is connected to the rotary holding fixture (15) for purposes of rotating the mould (1, 2)
9. The device in accordance with one of the Claims 6 to 8, characterised in that, the outer mould (2) and/or its segments (2a) has/have on its/their outer face at least one groove or channel (17) spiralling around its periphery, into which the tension cables (8) are laid during the winding process.
10. The device in accordance with one of the Claims 6 to 9, characterised in that, the inner mould (1) and/or the outer mould (2) is/are provided with heating channels and/or cooling channels.
11. The device in accordance with one of the Claims 1 to 10, characterised in that, the inner mould is provided with an automated contraction device (18), with which the inner segments (1a) can be pulled together for purposes of removing the component from the mould.

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